Consensus and Scalability Innovations BDC Practice Questions (Page 9)

Questions 41–45

1. 41foundation · easy

   Practical Byzantine Fault Tolerance (PBFT) is designed to work best in which type of blockchain?

   • APermissioned blockchains with a known set of validators
   • BBlockchains that use mining to secure the network
   • CPublic permissionless blockchains
   • DBlockchains that require no consensus
   Reveal Solution Discussion Select an answer first
2. 42expert · hard

   A consortium of enterprises runs separate permissioned blockchains (Hyperledger Fabric and Corda) and wants to enable asset transfers between them. They need to preserve the privacy of transactions within each network while allowing cross-network settlement. Which approach is most suitable?

   • AUse a public blockchain as a bridge and send all transaction data to it.
   • BUse a trusted interoperability protocol that uses atomic swaps or a notary scheme to coordinate transfers between the two networks.
   • CUse a sidechain that is shared by both networks, but allow each network to have its own consensus.
   • DMerge the two networks into a single blockchain to simplify interoperability.
   Reveal Solution Discussion Select an answer first
4. 43application · medium

   A developer is building a decentralized application that requires frequent, low-cost micro-transactions between users. They want to use a Layer 2 solution but also need to ensure that users can move their funds back to the main chain at any time. Which solution is most appropriate?

   • ASidechain, which has its own consensus and a two-way peg.
   • BPlasma, which uses child chains and fraud proofs.
   • COptimistic rollup, which batches transactions and posts them to the main chain.
   • DState channel, which allows users to transact off-chain and settle the final state on-chain.
   Reveal Solution Discussion Select an answer first
5. 44foundation · easy

   In Proof of Work (PoW), how is a new block added to the blockchain?

   • AA central authority signs and publishes the block
   • BA node solves a computationally difficult puzzle and broadcasts the solution
   • CA group of elected delegates votes to approve a block
   • DA node is randomly selected based on its coin balance
   Reveal Solution Discussion Select an answer first
6. 45application · medium

   A payment service provider wants to enable instant, low-cost transactions between its users without waiting for on-chain confirmation. They are willing to lock funds in a smart contract and require users to be online to settle. Which Layer 2 solution fits this requirement?

   • APlasma chains, which use a separate chain with periodic commitments to the main chain.
   • BState channels, where two parties lock funds on-chain and exchange signed messages off-chain, settling the final state on-chain.
   • CSidechains, which have their own consensus and do not require users to be online.
   • DOptimistic rollups, which batch all transactions into a single on-chain proof.
   Reveal Solution Discussion Select an answer first